Window openings may be of any width, depending on the building itself.
These are not usually made to any industry standard width.
Window coverings, such as shutters, shades, and blinds, must fill the width of the window space, as well as extending from top to bottom.
In the past simpler blinds and shades have been sold in a range standard widths.
Usually the range of widths covered widths, for example, of every 4 inches, ie, 30 inch, 34 inch, 38 inch, and so on. Ranges have varied from one maker to another.    The customer would specify the width of the window opening and the blind required.
The store assistant would then select an oversize blind.
The assistant would then cut down the width of the blind to the window opening width specified by the customer. The customer would then take the covering home and install it himself.
This system had the advantage that standard width coverings could be made, and sold, at lower prices.
The filling of the window opening from top to bottom was not usually a problem. The standard coverings could simply be made with excess length, which would not be apparent, once the covering was installed.
In some cases, with Venetian blinds, it was possible for the customer to adjust the length of the blind, if desired, in a relatively simple operation.
However this system, of trimming the width of coverings, involved the stores in buying special cut down machines. Assistants had to be trained in their use. Mistakes were made. Time was wasted.
Custom made coverings would solve these problems, but the costs were much higher, and customers were not willing to incur the expense.
This invention provides window opening edge space fillers. These are vertical strips, or extrusions which can attach to the side edges of the window frame (or even to the glass), and reduce the width of the window.
The fillers are adjustable and can enable the customer to reduce the width of the window opening, to one of the standard widths for window coverings, and thus accept a standard width covering.
This will mean there is no need for an assistant to cut the blind down to size.
The customer simply buys the covering and the window space fillers and installs them himself.
This will save the stores from maintaining cut down machines, and training staff.
This will also provide the store with an extra sale, ie the window space filler, each time the customer buys a standard width blind.
A further advantage is that it will now become possible for stores to stock a wider range of window coverings of different designs, and materials, all in ranges of standard widths. Coverings adaptable to this system may include Venetians, vertical blinds, shutters, shades, and roman shades, balloon shades, accordion pleat shades, and others
Such a variety of blinds, in many cases, simply could not be supplied to stores as standards and then “cut down”, under the old system, at all.
This will still further increase the sales volume of the stores.